Once upon a time there were three balloons.
A Daddy balloon, a Mommy balloon and a Baby balloon.
One night the baby balloon crept into his Daddy and Mommy's bedroom, and asked his Daddy if he could sleep in his bed with him.
'No you can't' said the Daddy balloon, 'Go back to your own bed'
The following night, the same thing, with the same result.
On the third night, the Baby balloon crept into his parents bedroom again, and tried to sneak into their bed without waking them up, but there wasn't enough room.
Then he had an idea, he gently let some air out of the Daddy balloon, and tried again, still not enough room.
He then let some air out of the Mommy balloon, and tried again, still not enough room.
He then let some air out of himself, and, bingo, there was enough room to get into his parents bed.
In the morning, when the Daddy balloon woke up. he was furious, 'I told you last night, and the night before to sleep in your own bed, not only have you let me down, you've let your Mommy down, and more importantly, you've let yourself down.'